Inspection systems for the analysis of moving web materials can be important in the manufacture of paper, non-woven materials, and polymeric films, as well as metal fabrication. These inspection systems can be used for both product certification and online process monitoring. However, with webs of commercially viable width, the web speeds that are typically used, and the pixel resolution that is typically needed in these manufacturing operations, data acquisition speeds of tens or even hundreds of megabytes per second are required, and it is a continual challenge to process images and to perform accurate defect detection at these data rates.
In addition, web process manufacturing operations can require multiple unit operations be performed on a single roll of material during its production. For example, certain complex web-based products, such as flexible circuits, may require as many as fifteen distinct manufacturing operations over the course of days or even weeks, often utilizing multiple production lines at different physical sites. In these circumstances, it is typical to collect the web into a roll after each process and ship the roll to a different location where it is then unrolled, processed, and again collected onto a different roll. Each process step may introduce new anomalies into a web, which may or may not cause the web to be defective when it is analyzed during a subsequent process step. Moreover, subsequent process steps can make it more difficult, if not impossible, to detect anomalies occurring in earlier process steps.